CN1315822A

CN1315822A - Film resistance element for printed circuit board and forming method thereof

Info

Publication number: CN1315822A
Application number: CN01103912.4A
Authority: CN
Inventors: 真道素志; 大摫充; 濑川惠嗣
Original assignee: Victor Company of Japan Ltd
Current assignee: Victor Company of Japan Ltd
Priority date: 2000-03-30
Filing date: 2001-02-12
Publication date: 2001-10-03
Also published as: US6411194B2; EP1139353A3; EP1139353A2; US20010026211A1

Abstract

The invention provides a production method capable of forming a thin film resistance element having a thickness and a shape controlled in a high accuracy in a printed circuit board. The production method has the steps of forming a thin film resistance layer having a predetermined thickness through an insulation layer by a dry process, forming an electrically conductive layer on the thin resistance layer, and etching the electrically conductive layer selectively so as to make, at least, a pair of electrically conductive pads, resulting in the thin film resistance element having a predetermined value of resistivity between the pair of electrically conductive pads. Thereby, it is possible to form the thin film resistance element having a thickness and a shape controlled in a high accuracy.

Description

Film resistance element of printed circuit board (PCB) and forming method thereof

The present invention relates to the formation method and the film resistance element of the film resistance element of printed circuit board (PCB).

Usually, require more miniaturization and the lightweight of printed circuit board (PCB) used in the various electronic equipments, wherein, thereby the requirement that the resistive element of how packing into had not only been kept the precision of its resistance value but also satisfied miniaturization is very important.As an example that forms such resistive element method, for example, using under the situation of ceramic substrate as printed circuit board (PCB), generally adopt widely in the wiring of this ceramic base plate surface, to apply resistance paste, and form the method for resistive element by print process.To be called the printed resistor body by the resistive element that this print process forms.

Below, the manufacture method of this printed resistor body is described with reference to Figure 10.In Figure 10, the 2nd, ceramic substrate, its surface is insulating barrier (state of insulation).At first, on this ceramic substrate 2, apply the conductive paste of forming by Ag-Pd cream etc., form the conductive layer pad 4 (Figure 10 (A)) that only separates predetermined distance by print process.

Then, apply resistance paste, make this resistance paste can be attached between the above-mentioned conductive layer pad 4 that separates, thereby form printed resistor body 6 by print process.

But the resistance value of above-mentioned printed resistor body 6 depends on that the coating of above-mentioned resistance paste forms size, i.e. resistance length L, resistance width W (not shown), thickness t.Like this, because because of the size of printed resistor body 6 causes resistance change, so the problem below existing.

At first, when above-mentioned conductive paste of silk screen printing and resistance paste, unavoidably second permeation, printing deviation etc. will take place, the resistance value of printed resistor body 6 can differentiated problem.

In addition, to roll the differences such as viscosity of printing conditions such as angle and resistance paste big because of being difficult to control rubber roll extrusion power, rubber for the thickness of especially above-mentioned resistance paste, and its result has the problem of the difference of the further resistance value that has strengthened printed resistor body 6.

In addition, material at conductive layer pad 4 is under the situation of copper, be difficult to obtain ohmic contact with this conductive layer pad, because may there be unnecessary resistance in the contact portion at conductive layer pad 4, so after printed resistor body 6 forms, have the problem that is difficult to obtain the desired resistance value of design load.

Therefore, this resistance value generally has ± about 30% deviation with respect to set point, must wait the shortcoming of adjusting resistance value by finishing in terminal stage so exist.

The present invention is conceived to solve above such problem and proposes, and its purpose is to provide the formation method and the film resistor of the film resistor of printed circuit board (PCB), can form the film resistor of controlling dimension and thickness accurately.

According to a first aspect of the invention, in the formation method of the film resistance element of printed circuit board (PCB), may further comprise the steps: thin film resistive layer forms step, forms the thin film resistive layer of specific thickness by the dry process that is used for the semiconductor processes etc. on the insulating barrier on the described printed circuit board (PCB); Conductive layer forms step, forms conductive layer on described thin film resistive layer; And film resistor not forms step, forms at least two conductive layer pads by corroding described conductive layer selectively, thereby forms the film resistor of regulation resistance value between described conductive layer pad.

Thus, can form the high thin film resistive layer of thickness precision, and form the conductive layer pad by photoetching process, so its planar dimension precision is also high, the result can suppress the deviation of the resistance value of film resistor, can this resistance value of High Accuracy Control.

In this case, as second aspect regulation, when being preferably in the formation of the composite base plate that stacks gradually insulating barrier and patterned conductive layer on the core material or hybrid multilayer substrate, form described film resistor.

A third aspect of the present invention is the film resistor of the method manufacturing of regulation by above-mentioned first aspect of the present invention, promptly comprises at the film resistance element on the printed circuit board (PCB): the thin film resistive layer of the formed specific thickness of dry process by being used for the semiconductor processes etc. on the insulating barrier on the described printed circuit board (PCB); And at least two conductive layer pads that on described thin film resistive layer, separate formation in order to form described film resistor.

In this case, as fourth aspect present invention, when described film resistor is to be set under the situation of film resistor of internal layer, be preferably in the recess that forms heat transmission on the insulating barrier on the top of this film resistor or near the conductive layer top it.Thus, can improve the thermal diffusivity of the heat that film resistor is produced.

Fig. 1 is the perspective view of first embodiment of expression film resistance element of the present invention.

Fig. 2 is the perspective view of second embodiment of expression film resistance element of the present invention.

Fig. 3 is the cutaway view of the 3rd embodiment of expression film resistance element of the present invention.

Fig. 4 is the process chart of the manufacture method of expression film resistance element.

Fig. 5 is the key diagram of explanation variation of the present invention.

Fig. 6 is the cutaway view of film resistance element that expression has the recess of heat radiation.

Fig. 7 is the cutaway view of another film resistance element that expression has the recess of heat radiation.

Fig. 8 is the cutaway view of another film resistance element that expression has the recess of heat radiation.

Fig. 9 is illustrated in the cutaway view that forms the situation of film resistor between the internal layer circuit figure.

Figure 10 is the process chart of the manufacture method of the existing printed resistor body of expression.

Below, an embodiment of the printed circuit board (PCB) that present invention will be described in detail with reference to the accompanying.

Fig. 1 is the perspective view of first embodiment of expression film resistance element of the present invention, and Fig. 2 is the perspective view of second embodiment of expression film resistance element of the present invention, and Fig. 3 is the cutaway view of the 3rd embodiment of expression film resistance element of the present invention.

The present invention adopts with the diverse method of existing method of using method for printing screen and forms film resistor.Shown in Fig. 1 (A), this film resistance element 10 is formed on the insulating barrier 14 on the surface that is positioned at printed circuit board (PCB) 12.In this case, this insulating barrier 14 can be the surface insulation layer of printed circuit board (PCB) 12 self, also can be at the insulating barrier that spreads all on the printed circuit board (PCB) 12 after multilayer is carried out multiple film forming, and which kind of insulating barrier all is suitable for.

Above-mentioned film resistance element 10 mainly by this above insulating barrier 14 by thickness t of illustrated example regulation film resistor 16 of forming of rectangular shape composition for example; And the formed pair of conductive layer pad 18 that for example is made of Cu constitutes on the both ends of this film resistor 16.The resistance value of this film resistance element 10 depends on the thickness t and the feature size of film resistor 16, in more detail, depends on resistance width W and resistance length L (distance between the opposite face of pair of conductive layer pad 18).

When forming above-mentioned film resistor 16, use the dry process of use in semiconductor processes etc.By in the film build method of this dry process, sputtering method, ion plating method, vapour deposition method, CVD method etc. are arranged.Advantage by the dry process film forming is, compares with the silk screen print method of using in the past, owing to thickness is controlled easily, so can high accuracy form the thickness of stipulating.In addition, in dry process, can adopt photoetching process on patterning process, this method is compared with silk screen print method, the pattern precision height.

In addition, when forming pair of conductive layer pad 18, on whole surface, form conductive layer, by only corroding this conductive layer (residual film resistive element 16 selectively, only corrode conductive layer), and only erode to given size (resistance length L * resistance width W), make the layer of the film resistor 16 of lower floor expose and form film resistor 16, can set resistance value arbitrarily thus.

As known from the above, can form the film resistor 16 higher by dry process than silk screen print method precision.

Have, above-mentioned film resistor 16 grades also can utilize the close-burning contact layer that is used to obtain insulating barrier (for example resin) and form the conductive layer (for example Cu) of conductive layer pad 18 to form again.

Although as illustrated in the first to file (special hope flat 11-95469 number), but, fine patternization descends because of making the caking property of conductive layer and insulating barrier, in existing surface treatment method, can not obtain sufficient caking property, so the applicant proposes to form contact layer by dry process between insulating barrier and conductive layer.This contact layer is implemented composition, with this as film resistor 16.As the material of this film resistor 16, can adopt various resistance materials such as Ni, Ni-Cr, Ni-Cu.

Like this, the film resistance element of first embodiment shown in Fig. 1 (A), 10 expression basic models, the film resistance element 10A shown in Fig. 1 (B) represent for example to change the embodiment of the width W 2 of film resistor 16.Second embodiment shown in Figure 2 represents conductive layer pad 18A with central authorities as shared pad, and the embodiment that for example the film resistance element 10A of shape is connected in series shown in the film resistance element 10 of shape shown in Fig. 1 (A) and Fig. 1 (B).Resistance length is expressed as L1 and L2 respectively.

In addition, the 3rd embodiment shown in Figure 3 adopts embodiments of the invention in compound (build-up) substrate (comprising hybrid multilayer substrate) that for example lamination insulating barrier and patterned conductive layer form successively on core material.That is, the film resistor 16A of lower floor and the film resistor 16B on upper strata are next stacked by insert insulating barrier 14A between it, and the conductive layer pad 18B that the both sides of above-mentioned two

film resistor

16A, 16B are for example formed by Cu respectively connects.Thus, two

film resistor

16A, 16B are connected in parallel.Wherein, the resistance length of each

film resistor

16A, 16B is expressed as L3 and L4 respectively.

The manufacture method of above-mentioned film resistance element is described below with reference to Fig. 4.

Wherein, as printed circuit board (PCB), so that be that example illustrates with the situation of the core material of for example hybrid multilayer substrate.

In Fig. 4 (A), the 20th, form the core material of Copper Foil 24 on the surface of the core 22 that constitutes by resin plate etc., this Copper Foil 24 for example carries out wet corrosion by photoetching and becomes internal layer figure 24A.The surface of layer pattern 24A in this is implemented surface treatments such as melanism processing and soft corrosion, form insulating barrier 14 by carrying out silk screen printing thereon.

Then, by dry type or wet processed this insulating barrier 14 is implemented surface treatment (roughening or activation are handled).

Then, shown in Fig. 4 (B), on this insulating barrier 14, will become material (for example, the Ni: use 99.9%) film forming, the thin film resistive layer 26 of deposit specific thickness (for example about 0.15 μ m) of resistive element by dry process (for example sputtering method).The membrance casting condition of this moment is that for example using gases is that Ar, gas pressure are that 0.4Pa (3mTorr), DC power supply are output as 400W, temperature is a normal temperature.At this moment, the deviation of the thickness of the thin film resistive layer 26 of above-mentioned sputtering method is about ± 5%, compares for ± 20% deviation with the thickness of the resistance paste of existing print process, and the thickness precision obviously improves.In addition, the dimensional accuracy during the figure of thin film resistive layer 26 forms is about ± 5%.

Then, obtain to electroplate conducting with this thin film resistive layer 26, shown in Fig. 4 (C), form the conductive layer 28 that for example is made of Cu by electroplating on this thin film resistive layer 26, forming by photoetching to become outer field figure again.Especially under the situation of using the high resistance material of resistivity,,, can carry out copper facing so after the formation of thin film resistive layer 26, form film Cu layer by waiting with sputter owing to be difficult for obtaining to electroplate conducting.The composition of this moment is that conductive layer 28 and thin film resistive layer 26 both sides are corroded.For example, under the situation of conductive layer Cu/ thin film resistive layer Ni,, can corrode simultaneously that this is two-layer if use copper chloride solution.In addition, conductive layer 28 and thin film resistive layer 26 can corrode respectively according to design specification, also can corrode simultaneously.

Then, shown in Fig. 4 (D),, for example apply the photic solid-state resist 30 that uses as diaphragm usually with silk screen printing as the mask material that is used for selective corrosion, by expose, developing forms the figure as film resistor.For corresponding with the caustic corrosion solution of following steps, this photic solid-state resist 30 also can use the resist with alkaline-resisting character.

Then, shown in Fig. 4 (E), as mask, only corrode above-mentioned conductive layer 28 with above-mentioned photic solid-state resist 30.Usually, the solution of corrosion Cu is acid solution, but uses alkaline solution for the thin film resistive layer 26 that stays the bottom, to have selectivity.As corrosive liquid, the A Treatment Solution that for example can use MELTEX company (メ Le テッ Network ス society) to produce.In addition, etching condition can second carry out with spray regime by temperature=45 ℃, time=60.Its result stays and will form the mask of the Cu of conductive layer 28, and all the other is eroded fully, thin film resistive layer 26 exposing surfaces under making.The result who surface analysis is carried out on the surface of the thin film resistive layer that exposes with ESCA (ALBUCKPHY company (ァ Le バッ Network Off Off ィ society) production) compares with surface state after the sputter, does not have difference on the peak volume of Ni.In addition, measure the thickness of the thin film resistive layer of forming by Ni 26, but with sputter after do not have difference.

Then, by peeling off the photoresist 30 as mask, shown in Fig. 4 (F), the conductive layer 28 that stays exposes as conductive layer pad 18 and forms.At this moment, the anticorrosive additive stripping liquid controlling-9296 (レジストストリッパ-9296) of peeling off use special-purpose liquid for example Japanese MCDUMID company (マ Network ダ-ミッ De society) production of photoresist 30.

Like this, by using photoetching treatment etc., the dimensional accuracy of the film resistor 16 of the composition shown in Fig. 4 (D), Fig. 4 (E) and Fig. 4 (F) is reached ± 5%, so with the resistance paste of existing silk screen print method ± 10% dimensional accuracy compares, and can carry out the management of high accuracy size.

In addition, be not limited to above-mentioned film resistor 16, resistive element is owing to energising is generated heat.The degree of its heating depends on current density, resistance material, state is set.For example, compare, clip poor radiation, therefore, have because of heating makes temperature and rise to become characteristic such as big because of the internal layer resistive element all is insulated layer (resin) up and down with outer resistive element.Also can be by following such thermal diffusivity that improves film resistor 16.

At first, compare,, just can apply big power by coming configured in series to have the short film resistor 16 of resistance length L 5 shown in Fig. 5 (A) with the long film resistor 16 shown in Fig. 5 (B) with resistance length L 6.At this moment, resistance length L 5, L6 have the relation shown in the following formula.

Resistance length L 5 * n (positive integer)=resistance length L 6

In addition, shown in Fig. 6 (A) and Fig. 6 (B), being insulated film 32 coverings at film resistor 16 becomes under the situation of internal layer, top at this film resistor 16, or on the insulating barrier 32 on the top of conductive layer in its vicinity (conductive layer pad 18), formation also can help heat radiation as the hole or the ditch of the recess 34 of heat transmission.In this illustrated example, be illustrated in the situation that forms recess 34 in the insulating barrier 32 of top of conductive layer pad 18.In addition, in this case, shown in Fig. 7 (A) and Fig. 7 (B),, be provided with the heat conduction layer 36 that conductive material is for example formed, also can help to improve radiating efficiency at the inner face of the recess 34 of above-mentioned heat transmission.

And, in this case, as shown in Figure 8, in described heat conduction layer 36, wait by photoetching, laser processing, roughened to form concavo-convex fin 38, increase its surface area, also can further improve the individual layer radiating efficiency.

In addition, though be that example is illustrated with the situation that forms film resistor at grade here, but be not limited to this, obviously, by the through hole that in insulating barrier, forms, even under the situation of bonding film resistive element, also can adopt the present invention between the circuitous pattern at grade or between the circuitous pattern of different layers.

For example, shown in Figure 9 is the cutaway view that forms the film resistor situation between the internal layer circuit figure.Shown in Fig. 9 (A), for example on the insulating barrier 42 that forms on the internal layer circuit figure 40 on core material 20 surfaces, form through hole 44, above-mentioned internal layer circuit figure 40 is exposed, the conductive layer 48 that on whole surface, stacks gradually thin film resistive layer 46 and for example constitute by Cu.

Then, shown in Fig. 9 (B),, above-mentioned conductive layer 48 and described thin film resistive layer 46 carry out composition (with reference to Fig. 4 (C)) by being corroded integratedly.Then, shown in Fig. 9 (C), by the Cu conductive layer 48 of the composition the superiors only selectively, thin film resistive layer 46 exposing surfaces (with reference to Fig. 4 (E) and Fig. 4 (F)) under can making.

So, form through hole 44, can form film resistor in position arbitrarily.

As described above, according to the film resistance element of printed circuit board (PCB) of the present invention Formation method and film resistance element, can bring into play following good action effect.

According to of the present invention first to the third aspect, can form accurately controlling dimension and thick The film resistor of degree, for example, in existing cream resistance, have with respect to setting value ± about 30% Deviation, and in film resistor of the present invention with respect to the setting value deviation can be suppressed to About ± 10%.

Its result can form the good film resistor of high accuracy and Ohmic contact.

According to a forth aspect of the invention, by film resistor or near the structural design it, The heat that produces from film resistor in the time of can distributing conducting expeditiously.

Claims

1. the formation method of the resistive element element of a printed circuit board (PCB), it is characterized in that, in this method, comprise following each step: thin film resistive layer forms step, by being used for the dry process of the semiconductor processes etc. on the insulating barrier on the described printed circuit board (PCB), form the thin film resistive layer of specific thickness; Conductive layer forms step, forms conductive layer on described thin film resistive layer; And film resistor formation step, form at least two conductive layer pads by corroding described conductive layer selectively, thereby between described conductive layer pad, form the film resistor of regulation resistance value.

2. the formation method of resistive element element as claimed in claim 1 is characterized in that, when stacking gradually the composite base plate of insulating barrier and patterned conductive layer or hybrid multilayer substrate on being formed on core material, forms described film resistor.

3. the film resistance element of a printed circuit board (PCB) is characterized in that, this element comprises: the thin film resistive layer of the formed specific thickness of dry process by being used for the semiconductor processes etc. on the insulating barrier on the printed circuit board (PCB); And at least two conductive layer pads that on described thin film resistive layer, separate formation in order to form described film resistor.

4. film resistance element as claimed in claim 3, it is characterized in that, under the situation of the film resistor that described film resistor is arranged on internal layer, on the insulating barrier on the top of this film resistor or near the conductive layer top it, form the recess of heat transmission.